Traditional computer system architectures typically include one or more dedicated computer servers for each application being run, and are often designed to include an excessive allocation of resources in order to be able to handle peak demands. Such partitioning of computer systems through dedicated servers and excessive allocation of resources can be costly, inefficient and difficult to scale and manage.
Virtualization, which refers to the abstraction of computer resources from their hardware or software-based physical constructs, is one manner of dealing with the aforementioned problems. One approach to virtualization is based on one or more virtual machines (VMs), each of which is a software implementation of a computer that executes programs or applications as if it was a physical computer. A virtual machine operates like a physical computer and contains, for example, its own virtual (e.g., software-based) central processing unit (CPU), random access memory (RAM), hard disk storage, and network interface card (NIC). Each virtual machine in a virtualization system generally runs its own guest operating system (OS), and the virtual machines generally share the underlying physical machine resources of the system.
Another approach to virtualization is based on one or more containers, each of which is allocated exclusive access to compute resources, using a separate name space that it may use to execute applications or programs, as if it was a separate operating system.
There are many potential benefits to operating in a virtualization system versus traditional architectures. For example, by permitting the sharing of hardware among applications workloads, virtualization can be used for improving resource utilization and reducing the need for excess resources to absorb peak traffic. Virtualization can also be used to improve the availability and robustness of applications, by shifting workloads among servers to handle fail-over situations. Similarly, virtualization provides flexible partitioning of applications, deployment, and operations. Notwithstanding the potential benefits, operating in a virtualization system presents several challenges and potential pitfalls, including significant operations management challenges.
For example, virtualization systems perform several input/output (I/O) intensive tasks—often concurrently. When multiple VMs or containers request to execute heavy-storage tasks at the same time (e.g., VM reboots, anti-virus database updates, OS updates, virus scans, and so on), storage controllers can face unrecoverable I/O congestion.
Conventional virtualization does not prioritize actions and account for resource impact of such actions. Managing resources in conventional virtualization systems includes evaluating alternative providers for a service or resource by comparing the attributes of the new service or resource and the current one. For example, when considering moving a VM, or a container, to a new storage device or array, conventional virtualization systems often consider the available storage amount and the data access latency of the new storage location, but ignore the time and resources it takes to move the VM, or container, to the new storage location. The impact of moving a VM can become significant when the amount of associated data to move is relatively large.
In addition, conventional virtualization systems render decisions based on the immediate impact of performing an action, rather than future impact (e.g., benefits) of an action. The virtualization systems may attempt to take into account a variety of parameters, such as how these parameters have evolved in the past, and how they are likely to evolve in the future. These systems, however, generally make decisions now (for the present time) and do not postpone decisions to the future. Moreover, in the past, predictions of future evolution have historically been rarely accurate.
Furthermore, conventional virtualization systems either do not allocate sufficient, or allocate too many, resources to an application that is initially deployed. In some systems, a default configuration is used. However, the default configuration may not be application-specific, may not consider the particular demand profile of the application, and/or cannot account for varying actual demand of the application. In other virtualization systems, modified configurations are based on best practices for an application type and/or artificial load tests in a simulated production environment. A single configuration generally cannot consider all possible application demands, and artificial load tests do not generally reflect with complete accuracy application demands in the production environment.
As an additional challenge, once an application is deployed, configurations are generally altered only in response to reported degradation in application performance. Performance metrics are collected and analyzed and the configuration can be manually changed to reflect a user's understanding of the correlation between the performance degradation and the existing configuration. Unfortunately, the resulting configuration is static and, again, best suited for a single level of demand. If application demand is less than the target of the resulting configuration, the system's resources will be overprovisioned and result in waste. Alternatively, if application demand exceeds the resulting configuration, the performance of the application is limited. In any case, altering configurations in conventional virtualization systems generally occur only after the application performance has degraded, whereas overprovisioning resources for a particular application is generally not subject to detection.
Additionally, current planning techniques for future application demands involve making assumptions about future changes in infrastructure capacity based on historical infrastructure utilization. For example, if the environment is currently utilized at a rate of 50% and the assumption is that application demand will increase by 20% in the next 12 months, then a conclusion is made that the environment will be utilized at a rate of 60% in 12 months. However, these assumptions are generally based on infrastructure changes—not application demand. Despite any relationship between application demand and infrastructure utilization, these assumptions are generally not based on actual data and can result in overprovisioning or in limiting resources for a particular application.
An alternative virtualization technique can be found in container systems. Container systems provide an operating-system level virtualization in which the kernel of an operating system can allow for multiple isolated user space instances. Stated another way, a container is based on server virtualization that uses a shared operating system. Rather than virtualizing hardware and creating whole virtual machines, each with their own operating systems, containers run atop the shared operating system kernel and file system that looks and feels like a complete, isolated instance of the operating system. Like shipping containers for cargo, these software containers can ship applications across different network-based systems (e.g., cloud computing based systems) and limit the impact of one container's activities on another container.
A container system may include software abstractions to virtualize computer resources (or compute resources) which are used by applications running in the container (“containerized” applications). The container system provides means to provision containers, allocate and control the resources available to a container, deploy and execute applications in the container, and facilitate full use of the container resources by such containerized applications, while isolating them from other applications, sharing the underlying resources. When a containerized application accesses a virtualized container resource (e.g., CPU, memory, storage I/O, Network I/O), the container system maps this access to a direct access of the underlying real resource.
Container systems, like virtual machine systems, provide means for abstracting computer resources (or compute resources), controlling and isolating the allocations of these resources to applications, distributing and migrating applications flexibly, among multiple servers, to support scalable, highly-available, robust and efficient datacenter (DC) and cloud systems. Additional information on containers can be found, for example, at Linux Containers (available at https://linuxcontainers.org), http://en.wikipedia.org/wiki/Docker_(software), and https://hadoop.apache.org/docs/r2.4.1/hadoop-yarn/hadoop-yarn-site/YARN.html, each of which is hereby incorporated by reference in its entirety and for all purposes.
Since containers are based on shared operating systems, unlike virtual machines, they do not require guest operating systems and thus avoid some of the overhead of virtual machines. For example, deploying and configuring a container may involve setting data structures to map container resources to server and OS resources. Therefore, deploying and configuring a container can often be accomplished in seconds; deploying a virtual machine and a guest OS and configuring both to run an application may require substantially more time. Studies have shown that container-virtualization can offer significant efficiencies and performance advantages over virtual-machines—e.g., see “An Updated Performance Comparison of Virtual Machines and Linux Containers,” by W. Felter et al., IBM Research, Jul. 21, 2014, available at http://domino.research.ibm.com/library/cyberdig.nsf/papers/0929052195DD819C85257D2300681E7B/$File/rc25482.pdf, the disclosure of which is hereby incorporated by reference in its entirety and for all purposes. According to various embodiments, for example, containers are less time consuming to deploy (e.g., seconds versus minutes), can be lightweight due to lack of operating system, require less overhead (e.g., 3% versus 20% memory overhead), and/or standardized (e.g., decoupled applications from the operating system(s)). As a result, for example, application density may increase by an order of magnitude.
A virtualization system may mix and match virtual machines and containers. For example, containers may run over virtual-machines. Additionally, a group of virtual machines may be containerized, much like any application, and executed by a container.
With lower overheads than VMs, the number of containers sharing a host is often an order of magnitude (e.g., 50-200) larger than the number of VMs (e.g., 5-20). Furthermore, containers perform a faster dynamic of change events (e.g., deploy, delete, increase/reduce resources, and so on). Accordingly, container system management presents challenging scalability and response time problems compared to VMs.
In view of the foregoing, a need exists for an improved resource management system and method for container control in an effort to overcome the aforementioned obstacles and deficiencies of conventional virtualization systems.